Journal of Engineering

This study provides an analysis of the thermal flow and behavior of the load-free refrigerator compartment. The main goal was to compare the thermal behavior inside the refrigerator cavity to the freezer door effect and install a fan on the freezer door while neglecting the heat transmitted by thermal radiation. The velocity distribution, temperature, and velocity path lines were theoretically studied. This was observed without affecting the shelves inside the cabinet and the egg and butter places on the refrigerator door as they were removed and the aluminum door replaced with a glass door. This study aims to expand our knowledge about the temperature and flow fields of this refrigerator model. Finally, the development of this work highlights the importance of numerical simulation in the search for improvements in the design of this refrigerator model, which may assist refrigerator manufacturers.

Plastic soil exhibits unfavorable geotechnical properties when saturated, causing negative defects to engineering structures. Various attempts have been made to improve these properties by using different materials, including problematic waste materials like cement kiln dust, to reduce environmental hazards. This paper explores the shrinkage, plasticity, and strength behavior of plastic soil enhanced with cement dust. Cement dust contents of 0%, 5%, 10%, 15%, and 20% by dry weight of soil were tested. Experimental series of shrinkage and plasticity tests and unconfined compression tests were conducted to explore the effects of cement dust on the quantitative amount of shrinkage, plasticity characteristics, and shear strength experienced by plastic soil. The effects of curing on soil strength were also investigated. The findings showed that the critical behavior and plasticity of plastic soil could be reduced by mixing the soil with 15% or 20% cement dust. The undrained shear strength, cu, of plastic soil-cement dust mixtures increased with the increasing dust content up to 20%. The best enhancement was attained when the content of cement dust was 20%, and the undrained shear strength was increased more than three times at this content.

This paper critically evaluates the gradation, fineness modulus, and clay content of various natural sands used for concrete work in Sulaymaniyah City, Iraq. Sixteen field sand samples were collected from Darbandikhan, Qalat Dizah, Koysinjaq, and Piramagroon. Sieve analysis was conducted on the oven-dry test specimens in compliance with ASTM C136. The test results were compared with American, British, and Iraqi specification standards (ASTM C33, BS 882, and IQS No. 45). Only three sands met the ASTM gradation limits, while others were coarser. Eight samples met the requirements of BS 882, and five samples met the limits of IQS No. 45. Only three sands had fineness modulus within the recommended ranges by ACI 211.1 and ACI 211.4. All sands included finer particles passing sieve size 0.075 mm. To improve particle size distributions, blending different sands is recommended.

This study aims to explore the influence of incorporating various percentages of slag as a replacement for fly ash in geopolymer concrete to promote sustainability in construction. The experimental work involved preparing geopolymer mixes using a blend of ground granulated blast-furnace slag (GGBFS) and low calcium fly ash class F activated by an alkaline solution. The mixture compositions of fly ash to slag were (0.75:0.25, 0.65:0.35, 0.55:0.45) by weight of cementitious materials, respectively. The results showed that the mix proportion of 0.45 blast furnace slag and 0.55 fly ash produced the best strength results. This mix ratio also provided a solution for the need for heat curing for fly ash-based geopolymer concrete. The study highlights the potential of using slag to enhance the mechanical properties of geopolymer concrete and reduce CO2 emissions.

Asphalt Hot Mix (HMA) is widely used in highway construction due to its economic advantages and ease of maintenance. However, various factors impact its performance, with aggregate gradation being a significant one. The Universal Specification for Roads and Bridges in Iraq (SCRB) limits different types of asphalt layers and allows for designed tolerance in aggregate gradation. Achieving the required job mix is challenging due to sieve control problems. This study focuses on the effects of aggregate gradation deviations by using original and modified asphalt binders with AC (40-50) and 4% SBS, respectively. A mid-gradation of the base asphalt mixture was selected as a reference mix, and more than 24 deviated mixtures were prepared. Typical Marshall routine studies were performed to assess the properties of the mixtures. Bailey's theory (CA, Fac ratios) was employed to understand the impact of these deviations on particle arrangement and blending performance. Results show that minor aggregate deviations do not greatly affect mixture performance, but significant deviations in coarse aggregates lead to a decrease in Marshall properties. The study aims to eliminate the effects of aggregate gradation deviations using 4% Styrene Butadiene Styrene (SBS) modified binder.

The main objective of this study is to understand the work of the pile caps made of lightweight aerated foam concrete and study the many factors affecting the ability and the capacity of the shear. The study was done by analyzing previous practical and theoretical experiences on the reinforced concrete pile caps. The previous practical results indicated that all specimens failed by shear diagonal compression or tension modes except one specimen that failed flexural-shear mode. Based on test specimens' practical results and behavior, some theoretical methods for estimating the ultimate strength of reinforced concrete pile caps have been recommended, some of which evolved into the design documents available on the subject. A theoretical and practical study of compression concluded that the shear capacity is limited by the nodal zone bearing stresses. The flexural capacity can be described by the column load that would cause the yielding of the tie (i.e., steel reinforcement). Therefore, the design of pile caps should include a check on bearing strength to be added to the traditional section force approach for pile cap design.